From: chris h

> On Fri, Sep 24, 2010 at 8:35 AM, Peter Lind <>
>       On 24 September 2010 14:22, Bob McConnell <> wrote:
>       > From: David Hutto
>       >
>       >> On Fri, Sep 24, 2010 at 4:09 AM, Gary
<> wrote:
>       >>> Daniel Kolbo wrote:
>       >>>
>       >>>> Say you have two classes: human and male.  Further, say
male extends
>       >>>> human.  Let's say you have a human object.  Then later you
want to make
>       >>>> that human object a male object.  This seems to be a pretty
>       >>>> thing to request of our objects.
>       >>>
>       >>> I don't think any human can change gender without major
surgery, but I
>       >>> don't know if you just chose your example badly or whether
you really
>       >>> think objects should be able to mutate into other types of
>       >>> without some kind of special treatment.
>       >>
>       >> But it would work in something like makehuman, where you
start with a neuter
>       >> form and scale one way or the other for physical features. If
>       >> remember correctly,
>       >> we're' all xx until you become xy(genetically speaking).
>       >
>       > This is one of the details that really bothers me about OOP.
It makes
> it impossible to implement some very reasonable scenarios. 80% of the
> when a patron is added to a system, we don't know which gender they
> More than 50% of the time, we will never know, since the client
doesn't keep
> track of it. But the rest of them will be assigned sometime after they
> added. i.e. the gender assignment comes from a secondary source that
is not
> available at the time the patron is entered.
>       >
>       If you can't handle that, it's not the fault of OOP but your
lack of
>       programming skills in OOP I'd say (and I mean no disrespect
there, I'm
>       just pretty sure your scenario can be handled very easily in
>       And no, I have no urge to defend OOP in PHP, I just see this
>       thread as a complete non-starter: if the language doesn't let
you do
>       something in a particular way, how about you stop, take a
>       then ask if perhaps there's a better way in the language to do
>       you want done? That would normally be a much more productive and
>       intelligent response than either a) pressing on in the face of
>       or b) complaining about your specific needs and how the language
>       to meet them.
> I think pages 17-19 of the GoF covers exactly this:
> "Object composition is an alternative to inheritance." ... "Any
> [composed] object can be replaced at run-time by another as long
> as it has the same type."
> I would look into "object composition" or just read the GoF.


Bob McConnell

PHP General Mailing List (
To unsubscribe, visit:

Reply via email to